[PATCH] kernel.h: Convert rounding macros to statement expressions, add ADD_MOD
in [Kernel]
|
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From: Joe Perches on 29 Mar 2010 17:20 On Mon, 2010-03-29 at 13:00 -0700, Joe Perches wrote: > On Mon, 2010-03-29 at 12:47 -0700, Randy Dunlap wrote: > > On Sun, 28 Mar 2010 14:57:27 -0700 Joe Perches wrote: > > > Add a macro for the somewhat common use of > > > (something + value) % value > > > because the test uses ADD_MOD > > > --- a/include/linux/kernel.h > > > +++ b/include/linux/kernel.h > > > +#define ADD_MOD(x, y) (((x) + (y)) % (y)) > > It would be better not to evaluate y more than one time. Do you prefer something like this? Convert rounding macros to statement expressions so arguments are only evaluated once. Add kernel-doc to rounding macros Add ADD_MOD statement expression for "(x + y) % y" Signed-off-by: Joe Perches <joe(a)perches.com> --- include/linux/kernel.h | 65 +++++++++++++++++++++++++++++++++++++++++------ 1 files changed, 56 insertions(+), 9 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index c96b1ac..6b92b20 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -55,15 +55,62 @@ extern const char linux_proc_banner[]; #define round_down(x, y) ((x) & ~__round_mask(x, y)) #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) -#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) -#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y)) -#define DIV_ROUND_CLOSEST(x, divisor)( \ -{ \ - typeof(divisor) __divisor = divisor; \ - (((x) + ((__divisor) / 2)) / (__divisor)); \ -} \ -) -#define ADD_MOD(x, y) (((x) + (y)) % (y)) + +/** + * roundup() - Returns x rounded up to the next whole multiple of y + * @x: dividend + * @y: divisor + * + * ie: roundup(4, 2) is 4, roundup(5, 2) is 6 + * c type conversion rules apply when x and y types differ + */ +#define roundup(x, y) \ +({ \ + typeof(y) _y = y; \ + ((x) + (_y - 1) / _y) * _y; \ +}) + +/** + * DIV_ROUND_UP() - Returns x/y rounded up to the next whole number + * @x: dividend + * @y: divisor + * + * ie: DIV_ROUND_UP(4, 2) is 2, DIV_ROUND_UP(5, 2) is 3 + * c type conversion rules apply when x and y types differ + */ +#define DIV_ROUND_UP(x, y) \ +({ \ + typeof(y) _y = y; \ + ((x) + _y - 1) / _y; \ +}) + +/** + * DIV_ROUND_CLOSEST() - Returns x/y rounded to the nearest whole number + * @x: dividend + * @y: divisor + * + * ie: DIV_ROUND_CLOSEST(4, 3) is 1, DIV_ROUND_CLOSEST(5, 3) is 2 + * c type conversion rules apply when x and y types differ + */ +#define DIV_ROUND_CLOSEST(x, y) \ +({ \ + typeof(y) _y = y; \ + ((x) + (_y / 2)) / _y; \ +}) + +/** + * ADD_MOD() - Returns (x + y) % y + * @x: initial value + * @y: value added to x then used as modulo + * + * ie: ADD_MOD(4, 2) is 0, ADD_MOD(5, 2) is 1 + * c type conversion rules apply when x and y types differ + */ +#define ADD_MOD(x, y) \ +({ \ + typeof(y) _y = y; \ + ((x) + _y) % _y; \ +}) #define _RET_IP_ (unsigned long)__builtin_return_address(0) #define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; }) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |